JP2011130382A - Image-capturing apparatus and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging device capable of performing automatic zoom control with respect to a plurality of objects, and to provide a method of controlling the device. <P>SOLUTION: An automatic zoom frame including a plurality of selected objects from among the objects detected from an imaged image is set. An imaging field angle is changed so that the entire automatic zoom frame is imaged. Setting of the automatic zoom frame and the change of the imaging field angle are executed continuously with respect to the imaged image. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus and a control method thereof, and more particularly, to an imaging apparatus capable of automatically adjusting a field angle of a zoom lens based on a detection result of a subject and a control method thereof.

  Conventionally, there has been proposed a video camera that detects an image of a subject from a captured image and automatically controls the angle of view of a zoom lens so that the area thereof falls within a predetermined range (see Patent Document 1). A video camera having such an automatic zoom control function has an advantage that the size of the subject in the captured image can be maintained substantially constant without the user manually adjusting the angle of view of the zoom lens.

JP-A-9-65197

  However, the video camera described in Patent Document 1 assumes a single face as a subject. For this reason, there is no disclosure or suggestion about automatic zoom control when it is desired to capture a plurality of subjects.

  SUMMARY OF THE INVENTION The present invention is intended to solve the above-described problems of the prior art, and provides an imaging apparatus capable of automatic zoom control for a plurality of subjects and a control method therefor.

  The above-described object is an imaging apparatus capable of changing the imaging angle of view, and includes a detection unit that detects a predetermined subject from a captured image, and a plurality of selected subjects among the detected subjects. A setting means for setting an image area including a subject as an automatic zoom frame, and a control means for changing an imaging angle of view so that the entire area of the automatic zoom frame is imaged. This is achieved by an imaging apparatus characterized in that the setting of the zoom frame and the change of the imaging angle of view are continuously performed on images that are continuously captured.

  With such a configuration, according to the present invention, it is possible to provide an imaging apparatus capable of automatic zoom control for a plurality of subjects and a control method therefor.

1 is a block diagram illustrating an example of a functional configuration of an imaging apparatus according to an embodiment of the present invention. The figure which shows typically the automatic zoom control in 1st Embodiment. 6 is a flowchart for explaining an automatic zoom control operation in the first embodiment. The figure which shows typically the automatic zoom control in 2nd Embodiment. 9 is a flowchart for explaining an automatic zoom control operation in the second embodiment.

<First Embodiment>
Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a block diagram illustrating a functional configuration example of an imaging apparatus according to an embodiment of the present invention. Note that the present invention can be applied to any imaging apparatus (and an apparatus including such an imaging apparatus) capable of detecting a subject and controlling the change of the imaging field angle. Specifically, the present invention can be applied to a digital video camera, a digital still camera, a mobile phone having a camera function, a portable information terminal, a media player, a personal computer, and the like, but is not limited thereto.

  In the following, an example in which the present invention is applied to an imaging apparatus including a zoom lens (optical zoom) that can optically change the angle of view will be described. However, an imaging apparatus capable of changing the angle of view (so-called digital zoom) by image processing The present invention can also be applied to.

  The imaging apparatus 100 includes a fixed lens 101 a, an angle of view adjustment lens 101 b, and a zoom lens 102 including a diaphragm 103. The light beam incident from the fixed lens 101 a forms an image on the image sensor 105 through the field angle adjusting lens 101 b and the diaphragm 103. An optical image of a subject formed on the image sensor 105 which is a photoelectric conversion element such as a CCD image sensor or a CMOS image sensor is converted into an analog image signal in pixel units. The analog image signal is converted into a digital image signal by an A / D converter (ADC) 106 and input to the camera signal processing unit 107. The camera signal processing unit 107 applies signal processing such as color signal processing, gain control processing, and white balance processing to the digital image signal, and outputs a video signal. When the video signal is encoded and recorded, the encoding process is also performed by the camera signal processing unit 107. The recording unit 108 records the video signal output from the camera signal processing unit 107 on the recording medium 109 in a predetermined recording format. The recording medium 109 may be a semiconductor memory, a magnetic recording medium, an optical recording medium, or the like. The recording medium 109 may be built in the imaging apparatus 100, detachable from the imaging apparatus 100, or a combination of both. Good.

  The subject detection unit 110 detects a predetermined subject (for example, a human face) from the video signal output by the camera signal processing unit 107, and outputs the position and size of the subject as a detection result. Since the subject detection in the subject detection unit 110 can be performed based on a known technique, the detailed description thereof is omitted. The automatic zoom calculation unit 111 calculates the angle of view (imaging angle of view) of the zoom lens 102 based on the detection result of the subject detection unit 110. Then, the automatic zoom calculation unit 111 controls the zoom motor 104 based on the calculation result, and adjusts the angle of view of the zoom lens 102 to the angle of view obtained by the calculation. The subject selection unit 112 is an operation unit for the user to select a plurality of subjects to be subjected to automatic zoom control. The subject selection unit 112 may be any key, switch, or the like that allows the user to select a region in the captured image displayed on the display unit 114, such as a touch panel, a direction key, and a determination key. The display unit 114 includes, for example, an LCD, displays a captured image from the camera signal processing unit 107, and based on the detection result of the subject detection unit 110, a mark (frame or the like) indicating the detected subject is captured in the captured image. Superimposed display.

  Note that the subject priority designation unit 113 is used in a second embodiment to be described later, and is not used in this embodiment. Therefore, it is not essential in the imaging apparatus 100 of the present embodiment. However, similar to the subject selection unit 112, the subject priority order designation unit 113 is used by the user to designate a desired subject from the image displayed on the display unit 114. It may also serve as the subject priority order specifying unit 113.

  Next, an automatic zoom control operation in the imaging apparatus according to the present embodiment will be described with reference to FIGS. The automatic zoom control operation can be executed in parallel with other processing (automatic focus detection processing, automatic exposure control processing, recording processing, etc.) during imaging standby of the imaging device or during moving image imaging. It is. In the following description, descriptions of these other processes are omitted.

  In the imaging apparatus 100 of the present embodiment, it is assumed that the display unit 114 functions as an electronic viewfinder during imaging standby or during moving image imaging. Specifically, the image sensor 105 continuously captures images and outputs an image signal for finder display at a predetermined frame rate (for example, 30 frames / second) from the camera signal processing unit 107. Then, by displaying the captured image signal on the LCD included in the display unit 114, the display unit 114 functions as an electronic viewfinder. The image signal for finder display has a resolution that matches the display resolution of the display unit 114 and generally has fewer pixels than the image signal for recording.

  Then, the subject detection unit 110 detects the subject from the image signal for finder display output from the camera signal processing unit 107. Here, assuming that the subject is a person's face, the subject detection unit 110 outputs a detection result indicating the size and position of a region (face region) that seems to be a person's face for each detected subject. When performing automatic zoom control during moving image recording, the subject detection unit 110 may detect the subject from the recording image. The subject detection is not necessarily performed for each frame, and may be performed every several frames. The frequency of subject detection (that is, the followability of automatic zoom control) can be appropriately determined according to the processing capability of the subject detection processing unit, the required followability of automatic zoom control, and the like.

  The display unit 114 superimposes and displays a mark (a face frame in this embodiment) indicating a region detected as a subject in the captured image from the detection result of the subject detection unit 110 on the captured image. In addition, since an imaging device having a face detection function and a face frame display function is well-known, description thereof will be omitted for further details.

  FIG. 2A shows an example of the display state of the display unit 114 in a state where two persons are detected as the subjects 204 and 205. Face frames 202 and 203 indicating the detected subject are superimposed on the faces of the persons 204 and 205 (S100). 2A shows the current angle of view of the zoom lens 102 together with the adjustable range of the angle of view of the zoom lens 102. W schematically represents the wide angle end (maximum field angle), T represents the telephoto end (minimum field angle), and 206 represents the current field angle.

  For example, the user can select a subject by operating a key or button for giving a subject selection start instruction included in the subject selection unit 112. For example, if the subject selection unit 112 has a touch panel that can specify arbitrary coordinates on the screen of the display unit 114, the user can use the touch panel to set the position in the face frame corresponding to the subject to be subject to automatic zoom control. By specifying, the subject can be selected. Alternatively, the subject can also be selected by operating the direction key of the subject selection unit 112 and pressing the enter key with the face frame corresponding to the desired subject selected. The method of selecting a subject from a display image is not the essence of the present invention, and any known method can be used.

  Here, if the user sequentially designates the face frames 202 and 203 of the subjects 204 and 205, information on the designation result (for example, coordinates on the image or information of the designated face frame) is automatically calculated from the subject selection unit 112. To the unit 111. The automatic zoom calculation unit 111 sets a rectangular frame including the face detection frame 202 of the subject 204 and the face detection frame 203 of the subject 205 as the automatic zoom frame 201 based on the information of the designation result and the detection result of the subject detection unit 110. (S102). The automatic zoom frame 201 can be set as a minimum rectangle circumscribing a plurality of face detection frames, but has a slight margin on the left and right in consideration of detection errors in the face area. Thus, it is possible to prevent a part of the face of the selected subject from being fit on the screen during the automatic zoom control. Also, from the viewpoint of the appearance of the captured image, it is desirable that there is a space around the subject, rather than the subject being at the edge of the screen. For the same reason, the automatic zoom frame 201 can be set with a slight margin above.

The automatic zoom calculation unit 111 calculates an angle of view (zoom position) such that the entire set automatic zoom frame 201 is included in the screen (S103). This calculation may be performed sequentially from the relationship between the amount of change in the zoom position (angle of view) and the enlargement / reduction ratio of the image, or may be performed by referring to a table that stores these relationships in advance. Further, the imaging angle of view may be calculated so that the entire automatic zoom frame 201 is imaged with an appropriate size (for example, as large as possible). The appropriate size of the automatic zoom frame 201 is determined in advance, for example, as a ratio (for example, 80% or more) that the size of the long side of the zoom frame 201 occupies the corresponding screen size (vertical or horizontal size). I can keep it.
Then, the automatic zoom calculation unit 111 drives the zoom motor 104 so that the zoom position (imaging field angle) obtained by the calculation is obtained (S104). The automatic zoom calculator 111 determines whether or not the angle of view after the change has reached a changeable maximum value (S105). Here, if the angle of view after the change does not reach the maximum value that can be changed, the processing from S102 is continuously executed based on the result of subject detection (S109) for the next captured image. The As described above, the automatic zoom control may not be continuously executed for each frame of images that are continuously captured. When automatic zoom control is performed every several frames, the start of subject detection processing is waited until an image to be processed next is captured.

  By repeatedly executing the zoom control described above, for example, in the state of FIG. 2A, when the subject 204 does not move and the subject 205 moves away from the subject 204 in the right direction, the automatic zoom calculation unit 111 sets. The horizontal length of the automatic zoom frame 201 increases. Therefore, control for increasing the angle of view of the zoom lens 102 (moving to the wide angle side) is performed (FIG. 2B). If the distance between the subjects 205 and 204 is shortened, the horizontal length of the automatic zoom frame 201 is reduced, so the automatic zoom calculation unit 111 decreases the angle of view of the zoom lens 102 (moves to the telephoto side). Take control. When the subject 205 further moves rightward from the state of FIG. 2B, the angle of view of the zoom lens 102 becomes maximum (S105, Yes). If the subject 205 continues to move to the right from the center of the image, the subject 205 moves outside the imaging range and is not detected by the subject detection unit 110, and the automatic zoom frame 201 including the subject 205 is set in the screen. Cannot be performed (S106, Yes).

  The automatic zoom calculation unit 111 starts counting elapsed time when any of the subjects to be included in the automatic zoom frame 201 cannot be detected by the subject detection unit 110 when the angle of view of the zoom lens 102 is the maximum (S107). . Then, subjects that cannot be detected continuously for a preset time are deleted from the selected subjects to be included in the automatic zoom frame 201 (S108). As shown in FIG. 2C, the automatic zoom calculation unit 111 includes the face frame of the selected subject other than the subject deleted in S108 based on the result of subject detection (S110) for the next captured image. A new automatic zoom frame 201 is set (S102). Thereby, the automatic zoom control based on the new automatic zoom frame 201 is continued (FIG. 2D).

  As described above, according to the present embodiment, an automatic zoom frame including a plurality of subject areas is set, and the angle of view is automatically adjusted so that the automatic zoom frame has a predetermined size with respect to the screen. By adjusting, it is possible to perform appropriate automatic zoom control for a plurality of subjects. If any of the plurality of subject areas to be included in the automatic zoom frame is not detected continuously for a predetermined time, a new auto zoom frame is set for a subject area other than the subject area. Continue automatic zoom control. Therefore, it is possible to perform appropriate automatic zoom control on the actually captured subject without the user selecting the subject again.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. The imaging apparatus according to the present embodiment is different from the first embodiment in that a subject priority order specifying unit 113 is used instead of the subject selection unit 112 in the configuration shown in FIG.

  Therefore, the subject selection unit 112 is not essential in the imaging apparatus 100 of the present embodiment. However, as described above, the subject priority order specifying unit 113 and the subject selecting unit 112 are configured to allow the user to specify a desired subject from the image displayed on the display unit 114, and thus subject priority is practically given. The rank designation unit 113 may also serve as the subject selection unit 112.

  In the first embodiment described above, a plurality of selected subjects are handled in the same row. Therefore, for example, when the main subject that the user wants to preferentially capture is the subject 204, and the subject 205 is an accompanying subject with a low priority, the size of the main subject may be undesired by the user due to the movement of the accompanying subject. There is. Specifically, as shown in FIG. 2B, when the associated subject 205 moves away from the main subject 204 and the size of the long side of the automatic zoom frame 201 is enlarged, the angle of view is increased accordingly. Therefore, the size of the main subject 204 on the screen is reduced. In the automatic zoom control according to the first embodiment, since the reduction in the size of the main subject 204 is not taken into consideration, there is a possibility that the main subject 204 is imaged at a size (small) that is not desired by the user.

  On the other hand, in the present embodiment, when the user selects a subject to be subjected to automatic zoom control, the subject priority order designation unit 113 can designate the priority order of each subject. Then, the automatic zoom calculation unit 111 performs automatic zoom control so that the main subject is imaged while maintaining a predetermined size.

  Next, an automatic zoom control operation in the imaging apparatus according to the present embodiment will be described with reference to FIGS. 4 and FIG. 5, the same reference numerals as those in FIG. 2 and FIG. 3 are used for the same configurations and processing steps as those in the first embodiment, and duplicate explanations are omitted.

FIG. 4A shows an example of the display state of the display unit 114 in a state where two persons 204 and 205 are detected as subjects, similarly to FIG. 2A (S100).
Here, for example, the user can perform subject selection and subject priority designation by operating a key or button for giving a subject selection start instruction included in the subject priority order designation unit 113. For example, it is assumed that the subject priority order specifying unit 113 has a touch panel that can specify arbitrary coordinates on the screen of the display unit 114. In this case, the user can specify the subject selection and the priority order by designating the position in the face frame corresponding to the subject to be subjected to the automatic zoom control on the touch panel in the descending order of priority. Alternatively, by operating the direction key of the subject priority order specifying unit 113 to select the face frame corresponding to the desired subject and pressing the enter key in order from the subject with the highest priority order. Selection can be made.

  Here, an example of an operation method in which subject selection and priority order designation are performed simultaneously has been described, but subject selection and priority order designation may be performed independently. The priority order of the subject does not necessarily have to be different for each of the selected subjects. Only the subject (main subject) having the highest priority among the selected subjects is specified, and the priority order of the other subjects is selected. May be treated as the same line. In this case, when the selection of the subject to be subjected to automatic zoom control is completed, the user may designate the main subject from the selected subjects. In addition, among the selected subjects, the subject closest to the center of the image may be automatically set as the main subject, and other subjects may be handled as the accompanying subjects. In this case, the user does not need to specify the priority order of the subject. The selection of the subject and the specification of the priority order are both operations for specifying the subject, and the operation method itself is not the essence of the present invention, and any known method can be used.

  Here, the subject 204 and the subject 205 are selected as subjects for automatic zoom control, and the priority of the subject 204 is designated as the first (main subject), and the priority of the subject 205 is designated as the second (accompanying subject). It is assumed (S201). Information on the designation result (for example, coordinates on the image or information on the designated face frame) and priority order information are given from the subject priority order designation unit 113 to the automatic zoom calculation unit 111. The automatic zoom calculation unit 111 sets a rectangular frame including the face detection frame 202 of the subject 204 and the face detection frame 203 of the subject 205 as the automatic zoom frame 201 based on the information of the designation result and the detection result of the subject detection unit 110. (S102).

  In step S203, the automatic zoom calculation unit 111 detects the amount of movement of the main subject 204 and the accompanying subject 205 from the center of the image from the previous processing time point. The automatic zoom calculation unit 111 stores, for example, the positions of the face frames of the most recent main subject 204 and the accompanying subject 205 and obtains the difference between the current face frame position obtained from the subject detection unit 110 and the subject. The amount of movement can be detected.

  If the amount of movement of the main subject 204 is greater than or equal to the amount of movement of the accompanying subject 205 (S203, No), the automatic zoom calculation unit 111 calculates the zoom position in S103 as in the first embodiment, and the zoom motor 104 in S104. To automatically control the zoom position (view angle). This control is schematically shown in FIGS. 4 (c) and 4 (d).

  On the other hand, when the movement amount of the accompanying subject 205 is larger (S203, Yes), the automatic zoom calculation unit 111 calculates the face frame size of the main subject when automatic zoom control is performed, and determines whether it is larger than the threshold value. (S206). If the value is larger than the threshold value, the automatic zoom calculation unit 111 performs automatic zoom using the latest automatic zoom frame set in S102 (S103, S104). However, when the automatic zoom control is performed and the size of the face frame of the main subject 204 is equal to or smaller than the threshold, the automatic zoom calculation unit 111 stops the automatic zoom control (to the wide angle side) and sets the current angle of view. maintain. For example, when the accompanying subject 205 moves to the right from the state shown in FIG. 4A and further moves to the right in the state shown in FIG. 4B, it is determined that the face frame size of the main subject is equal to or smaller than the threshold value. For example, the automatic zoom control from the state of FIG. 4B to the wide angle side is stopped, and the angle of view is maintained (not changed). If the accompanying subject 205 further moves, there is a possibility that at least a part of the accompanying subject 205 is not captured, but the size of the main subject 204 is given priority.

  As described above, automatic zoom control with respect to a plurality of subjects is also possible according to this embodiment. In particular, in the present embodiment, priorities are assigned to a plurality of subjects for which automatic zoom control is performed, and automatic zoom control is performed within a range in which the size of subjects with high priorities does not fall below a threshold value. For this reason, it is possible to prevent the size of the subject with the higher priority from becoming too small due to the movement of the subject with the lower priority.

(Other embodiments)
Although the present invention has been described in detail based on preferred embodiments thereof, the present invention is not limited to these specific embodiments, and various forms within the scope of the present invention are also included in the present invention. included. A part or all of the above-described embodiments may be appropriately combined. Specifically, also in the second embodiment, as in the first embodiment, the accompanying subject that has moved out of the imaging range may be excluded from the target of automatic zooming. For example, when the accompanying subject 205 moves outside the screen in the state where the automatic zoom control to the wide angle side is stopped in S207, the automatic zoom frame can be reset except for the accompanying subject 205.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (5)

An imaging device capable of changing an imaging angle of view,
Detection means for detecting a predetermined subject from the captured image;
A setting means for setting an area of the image including a plurality of subjects selected by the user among the detected subjects as an automatic zoom frame;
Control means for changing the imaging angle of view so that the entire area of the automatic zoom frame is imaged,
An imaging apparatus, wherein the detection of the subject, the setting of the automatic zoom frame, and the change of the imaging field angle are continuously performed on images that are continuously captured.   When at least one of the plurality of subjects has moved out of the imaging range when the imaging field angle is maximized, the setting unit is configured to apply the subject to the subject excluding the moved subject among the plurality of subjects. The image pickup apparatus according to claim 1, wherein an automatic zoom frame is set.   The control means changes the imaging field angle within a range in which a size of a subject designated as a main subject among the plurality of subjects does not fall below a predetermined threshold. The imaging device according to claim 1 or 2.   The imaging apparatus according to claim 3, further comprising a designation unit that designates a subject closest to a center of the captured image as the main subject among the plurality of subjects. An imaging apparatus control method capable of changing an imaging angle of view,
A detection step of detecting a predetermined subject from the captured image;
A setting step of setting an area of the image including a plurality of subjects selected by the user among subjects detected in the detection step as an automatic zoom frame;
A control step of changing the imaging angle of view so that the entire area of the automatic zoom frame is imaged,
A method for controlling an imaging apparatus, wherein the detection step, the setting step, and the control step are continuously performed on images that are continuously captured.

Images